forked from KolibriOS/kolibrios
108 lines
3.4 KiB
C
108 lines
3.4 KiB
C
/*
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Copyright (C) 1997--2004, Makoto Matsumoto, Takuji Nishimura, and
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Eric Landry; All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer
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in the documentation and/or other materials provided with the
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distribution.
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3. The names of its contributors may not be used to endorse or
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promote products derived from this software without specific
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prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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Any feedback is very welcome.
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http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
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email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
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Reference: M. Matsumoto and T. Nishimura, "Mersenne Twister:
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A 623-Dimensionally Equidistributed Uniform Pseudo-Random Number
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Generator", ACM Transactions on Modeling and Computer Simulation,
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Vol. 8, No. 1, January 1998, pp 3--30.
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*/
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#include "mtrand.h"
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/* Period parameters */
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#define N 624
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#define M 397
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#define MATRIX_A 0x9908b0dfUL /* constant vector a */
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#define UPPER_MASK 0x80000000UL /* most significant w-r bits */
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#define LOWER_MASK 0x7fffffffUL /* least significant r bits */
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static unsigned long x[N]; /* the array for the state vector */
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static unsigned long *p0, *p1, *pm;
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void mt_srand( unsigned long s )
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{
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int i;
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x[0] = s & 0xffffffffUL;
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for (i = 1; i < N; ++i) {
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x[i] = (1812433253UL * (x[i - 1] ^ (x[i - 1] >> 30)) + i)
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& 0xffffffffUL; /* for >32 bit machines */
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}
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p0 = x;
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p1 = x + 1;
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pm = x + M;
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}
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/* generates a random number on the interval [0,0xffffffff] */
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unsigned long mt_rand( void )
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{
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unsigned long y;
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if (!p0) {
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/* Default seed */
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mt_srand(5489UL);
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}
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/* Twisted feedback */
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y = *p0 = *pm++ ^ (((*p0 & UPPER_MASK) | (*p1 & LOWER_MASK)) >> 1) ^ ((~(*p1 & 1)+1) & MATRIX_A);
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p0 = p1++;
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if (pm == x + N) {
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pm = x;
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}
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if (p1 == x + N) {
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p1 = x;
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}
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/* Temper */
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y ^= y >> 11;
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y ^= y << 7 & 0x9d2c5680UL;
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y ^= y << 15 & 0xefc60000UL;
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y ^= y >> 18;
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return y;
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}
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/* generates a random number on the interval [0,1]. */
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float mt_rand_1( void )
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{
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return ((float)mt_rand() / (float)MT_RAND_MAX);
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}
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/* generates a random number on the interval [0,1). */
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float mt_rand_lt1( void )
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{
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/* MT_RAND_MAX must be a float before adding one to it! */
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return ((float)mt_rand() / ((float)MT_RAND_MAX + 1.0f));
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}
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